1 /*

     2  * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 #include "incls/_precompiled.incl"

    26 #include "incls/_heapRegionSeq.cpp.incl"

    27 

    28 // Local to this file.

    29 

    30 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {

    31   if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;

    32   else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;

    33   else if (*hr1p == *hr2p) return 0;

    34   else {

    35     assert(false, "We should never compare distinct overlapping regions.");

    36   }

    37   return 0;

    38 }

    39 

    40 HeapRegionSeq::HeapRegionSeq() :

    41   _alloc_search_start(0),

    42   // The line below is the worst bit of C++ hackery I've ever written

    43   // (Detlefs, 11/23).  You should think of it as equivalent to

    44   // "_regions(100, true)": initialize the growable array and inform it

    45   // that it should allocate its elem array(s) on the C heap.  The first

    46   // argument, however, is actually a comma expression (new-expr, 100).

    47   // The purpose of the new_expr is to inform the growable array that it

    48   // is *already* allocated on the C heap: it uses the placement syntax to

    49   // keep it from actually doing any allocation.

    50   _regions((ResourceObj::operator new (sizeof(GrowableArray<HeapRegion*>),

    51                                        (void*)&_regions,

    52                                        ResourceObj::C_HEAP),

    53             100),

    54            true),

    55   _next_rr_candidate(0),

    56   _seq_bottom(NULL)

    57 {}

    58 

    59 // Private methods.

    60 

    61 HeapWord*

    62 HeapRegionSeq::alloc_obj_from_region_index(int ind, size_t word_size) {

    63   assert(G1CollectedHeap::isHumongous(word_size),

    64          "Allocation size should be humongous");

    65   int cur = ind;

    66   int first = cur;

    67   size_t sumSizes = 0;

    68   while (cur < _regions.length() && sumSizes < word_size) {

    69     // Loop invariant:

    70     //  For all i in [first, cur):

    71     //       _regions.at(i)->is_empty()

    72     //    && _regions.at(i) is contiguous with its predecessor, if any

    73     //  && sumSizes is the sum of the sizes of the regions in the interval

    74     //       [first, cur)

    75     HeapRegion* curhr = _regions.at(cur);

    76     if (curhr->is_empty()

    77         && !curhr->is_reserved()

    78         && (first == cur

    79             || (_regions.at(cur-1)->end() ==

    80                 curhr->bottom()))) {

    81       sumSizes += curhr->capacity() / HeapWordSize;

    82     } else {

    83       first = cur + 1;

    84       sumSizes = 0;

    85     }

    86     cur++;

    87   }

    88   if (sumSizes >= word_size) {

    89     _alloc_search_start = cur;

    90     // Mark the allocated regions as allocated.

    91     bool zf = G1CollectedHeap::heap()->allocs_are_zero_filled();

    92     HeapRegion* first_hr = _regions.at(first);

    93     for (int i = first; i < cur; i++) {

    94       HeapRegion* hr = _regions.at(i);

    95       if (zf)

    96         hr->ensure_zero_filled();

    97       {

    98         MutexLockerEx x(ZF_mon, Mutex::_no_safepoint_check_flag);

    99         hr->set_zero_fill_allocated();

   100       }

   101       size_t sz = hr->capacity() / HeapWordSize;

   102       HeapWord* tmp = hr->allocate(sz);

   103       assert(tmp != NULL, "Humongous allocation failure");

   104       MemRegion mr = MemRegion(tmp, sz);

   105       SharedHeap::fill_region_with_object(mr);

   106       hr->declare_filled_region_to_BOT(mr);

   107       if (i == first) {

   108         first_hr->set_startsHumongous();

   109       } else {

   110         assert(i > first, "sanity");

   111         hr->set_continuesHumongous(first_hr);

   112       }

   113     }

   114     HeapWord* first_hr_bot = first_hr->bottom();

   115     HeapWord* obj_end = first_hr_bot + word_size;

   116     first_hr->set_top(obj_end);

   117     return first_hr_bot;

   118   } else {

   119     // If we started from the beginning, we want to know why we can't alloc.

   120     return NULL;

   121   }

   122 }

   123 

   124 void HeapRegionSeq::print_empty_runs(bool reserved_are_empty) {

   125   int empty_run = 0;

   126   int n_empty = 0;

   127   bool at_least_one_reserved = false;

   128   int empty_run_start;

   129   for (int i = 0; i < _regions.length(); i++) {

   130     HeapRegion* r = _regions.at(i);

   131     if (r->continuesHumongous()) continue;

   132     if (r->is_empty() && (reserved_are_empty || !r->is_reserved())) {

   133       assert(!r->isHumongous(), "H regions should not be empty.");

   134       if (empty_run == 0) empty_run_start = i;

   135       empty_run++;

   136       n_empty++;

   137       if (r->is_reserved()) {

   138         at_least_one_reserved = true;

   139       }

   140     } else {

   141       if (empty_run > 0) {

   142         gclog_or_tty->print("  %d:%d", empty_run_start, empty_run);

   143         if (reserved_are_empty && at_least_one_reserved)

   144           gclog_or_tty->print("(R)");

   145         empty_run = 0;

   146         at_least_one_reserved = false;

   147       }

   148     }

   149   }

   150   if (empty_run > 0) {

   151     gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);

   152     if (reserved_are_empty && at_least_one_reserved) gclog_or_tty->print("(R)");

   153   }

   154   gclog_or_tty->print_cr(" [tot = %d]", n_empty);

   155 }

   156 

   157 int HeapRegionSeq::find(HeapRegion* hr) {

   158   // FIXME: optimized for adjacent regions of fixed size.

   159   int ind = hr->hrs_index();

   160   if (ind != -1) {

   161     assert(_regions.at(ind) == hr, "Mismatch");

   162   }

   163   return ind;

   164 }

   165 

   166 

   167 // Public methods.

   168 

   169 void HeapRegionSeq::insert(HeapRegion* hr) {

   170   if (_regions.length() == 0

   171       || _regions.top()->end() <= hr->bottom()) {

   172     hr->set_hrs_index(_regions.length());

   173     _regions.append(hr);

   174   } else {

   175     _regions.append(hr);

   176     _regions.sort(orderRegions);

   177     for (int i = 0; i < _regions.length(); i++) {

   178       _regions.at(i)->set_hrs_index(i);

   179     }

   180   }

   181   char* bot = (char*)_regions.at(0)->bottom();

   182   if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;

   183 }

   184 

   185 size_t HeapRegionSeq::length() {

   186   return _regions.length();

   187 }

   188 

   189 size_t HeapRegionSeq::free_suffix() {

   190   size_t res = 0;

   191   int first = _regions.length() - 1;

   192   int cur = first;

   193   while (cur >= 0 &&

   194          (_regions.at(cur)->is_empty()

   195           && !_regions.at(cur)->is_reserved()

   196           && (first == cur

   197               || (_regions.at(cur+1)->bottom() ==

   198                   _regions.at(cur)->end())))) {

   199       res++;

   200       cur--;

   201   }

   202   return res;

   203 }

   204 

   205 HeapWord* HeapRegionSeq::obj_allocate(size_t word_size) {

   206   int cur = _alloc_search_start;

   207   // Make sure "cur" is a valid index.

   208   assert(cur >= 0, "Invariant.");

   209   HeapWord* res = alloc_obj_from_region_index(cur, word_size);

   210   if (res == NULL)

   211     res = alloc_obj_from_region_index(0, word_size);

   212   return res;

   213 }

   214 

   215 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {

   216   iterate_from((HeapRegion*)NULL, blk);

   217 }

   218 

   219 // The first argument r is the heap region at which iteration begins.

   220 // This operation runs fastest when r is NULL, or the heap region for

   221 // which a HeapRegionClosure most recently returned true, or the

   222 // heap region immediately to its right in the sequence.  In all

   223 // other cases a linear search is required to find the index of r.

   224 

   225 void HeapRegionSeq::iterate_from(HeapRegion* r, HeapRegionClosure* blk) {

   226 

   227   // :::: FIXME ::::

   228   // Static cache value is bad, especially when we start doing parallel

   229   // remembered set update. For now just don't cache anything (the

   230   // code in the def'd out blocks).

   231 

   232 #if 0

   233   static int cached_j = 0;

   234 #endif

   235   int len = _regions.length();

   236   int j = 0;

   237   // Find the index of r.

   238   if (r != NULL) {

   239 #if 0

   240     assert(cached_j >= 0, "Invariant.");

   241     if ((cached_j < len) && (r == _regions.at(cached_j))) {

   242       j = cached_j;

   243     } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {

   244       j = cached_j + 1;

   245     } else {

   246       j = find(r);

   247 #endif

   248       if (j < 0) {

   249         j = 0;

   250       }

   251 #if 0

   252     }

   253 #endif

   254   }

   255   int i;

   256   for (i = j; i < len; i += 1) {

   257     int res = blk->doHeapRegion(_regions.at(i));

   258     if (res) {

   259 #if 0

   260       cached_j = i;

   261 #endif

   262       blk->incomplete();

   263       return;

   264     }

   265   }

   266   for (i = 0; i < j; i += 1) {

   267     int res = blk->doHeapRegion(_regions.at(i));

   268     if (res) {

   269 #if 0

   270       cached_j = i;

   271 #endif

   272       blk->incomplete();

   273       return;

   274     }

   275   }

   276 }

   277 

   278 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {

   279   int len = _regions.length();

   280   int i;

   281   for (i = idx; i < len; i++) {

   282     if (blk->doHeapRegion(_regions.at(i))) {

   283       blk->incomplete();

   284       return;

   285     }

   286   }

   287   for (i = 0; i < idx; i++) {

   288     if (blk->doHeapRegion(_regions.at(i))) {

   289       blk->incomplete();

   290       return;

   291     }

   292   }

   293 }

   294 

   295 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,

   296                                    size_t& num_regions_deleted) {

   297   assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");

   298   assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");

   299 

   300   if (_regions.length() == 0) {

   301     num_regions_deleted = 0;

   302     return MemRegion();

   303   }

   304   int j = _regions.length() - 1;

   305   HeapWord* end = _regions.at(j)->end();

   306   HeapWord* last_start = end;

   307   while (j >= 0 && shrink_bytes > 0) {

   308     HeapRegion* cur = _regions.at(j);

   309     // We have to leave humongous regions where they are,

   310     // and work around them.

   311     if (cur->isHumongous()) {

   312       return MemRegion(last_start, end);

   313     }

   314     cur->reset_zero_fill();

   315     assert(cur == _regions.top(), "Should be top");

   316     if (!cur->is_empty()) break;

   317     shrink_bytes -= cur->capacity();

   318     num_regions_deleted++;

   319     _regions.pop();

   320     last_start = cur->bottom();

   321     // We need to delete these somehow, but can't currently do so here: if

   322     // we do, the ZF thread may still access the deleted region.  We'll

   323     // leave this here as a reminder that we have to do something about

   324     // this.

   325     // delete cur;

   326     j--;

   327   }

   328   return MemRegion(last_start, end);

   329 }

   330 

   331 

   332 class PrintHeapRegionClosure : public  HeapRegionClosure {

   333 public:

   334   bool doHeapRegion(HeapRegion* r) {

   335     gclog_or_tty->print(PTR_FORMAT ":", r);

   336     r->print();

   337     return false;

   338   }

   339 };

   340 

   341 void HeapRegionSeq::print() {

   342   PrintHeapRegionClosure cl;

   343   iterate(&cl);

   344 }